47P/Ashbrook-Jackson (0047P)

Type: Periodic Perihelion date: 27 October 2025 Perihelion distance (q): 2.8 Aphelion distance (Q) : 5.4 Period (years): 8.4 Eccentricity (e): 0.32 Inclination (i): 13.0 JPL orbit diagram COBS lightcurve Atlas This comet was independently discovered by astronomers in the United States and South Africa. The first discovery was made by Yale astronomer Joseph Ashbrook. Ashbrook was visiting Lowell Observatory (Arizona, USA) to observe minor planets. While examining a photo exposed on 26 August 1948 for asteroid 1327 Namaqua, he found the comet and said it appeared diffuse, with a short tail. Twelve hours later, Cyril Jackson (Yale-Columbia Station, Johannesburg, South Africa) was experimenting with a 50-cm focus camera to test its ability to photograph fast moving minor planets. This comet was revealed on one of the plates. The comet has been observed at every return following the 1948 discovery. Despite the large perihelion distance it typically reaches a magnitude brighter than 12 as it is one of the intrinsically brightest short-period comets. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 20-Jul-17 17.53 0.03 16.4 0.3 30-Jul-17 17.52 0.04 16.5 0.3 25-Aug-17 17.15 0.03 16.4 0.3 28-Aug-17 17.19 0.03 16.0 0.4 16-Sep-17 16.99 0.01 16.0 0.6 27-Sep-17 16.89 0.04 15.8 0.6 23-Nov-17 17.39 0.02 16.3 0.3 04-Jan-18 18.25 0.04 17.1 0.3 14-Feb-18 18.77 0.05 18.4 0.2